This invention relates to a system and method for protecting a vehicle catalytic converter through which the vehicle engine exhaust gases pass against overtemperature and specifically against an overtemperature condition resulting from ignition misfire or a fueling condition of a particular cylinder of the vehicle engine.
In order to minimize the amounts of certain engine exhaust gas components discharged into the atmosphere, it is common in automotive vehicles to utilize a catalytic converter through which engine exhaust gases are discharged to the atmosphere and which is effective to reduce the amounts of those exhaust gas components. For example, three-way catalytic converters are typically employed to oxidize carbon monoxides and hydrocarbons and to reduce nitrogen oxides.
If the catalytic converter is heated to excessive levels, there is a potential for damage to the converter. One potential cause of excessive converter temperature is ignition misfire that results in unburned hydrocarbons and carbon monoxides being discharged into the exhaust system. Another cause is a faulty injector delivering excessive fuel to a particular cylinder of the engine resulting in unburned hydrocarbons being discharged into the exhaust system. In both cases, the resulting oxidation of those hydrocarbons and carbon monoxides in the converter elevates the temperature of the converter giving rise to the potential overtemperature condition. It is desirable to protect the converter from this overtemperature condition that results from a misfire or other fueling condition of a particular cylinder of the engine.